The world is out to get you. That's how I ended up feeling after compiling this list of horrifying, permanently scarring, eternally terrifying rare diseases. Genetic, infectious, parasitic and everything in-between, these 15 diseases scar their victims for life and scar us mentally having looked at them.

15. Blaschko's Lines

So, it turns out we all have Blaschko's Lines, but they’re invisible under normal conditions, until they show up due to a bunch of different disorders that can cause the pigmentation on your skin to change. The lines show up as a v-shape on the back, an s-shape on the front, and weird wavy lines all over your head. They think the lines are formed from where the embryonic cells are transported in utero, but the weirdest thing is there are more than nine different diseases that can cause you to be striped like a freaking zebra.

14. Guinea Worm

Guinea worm disease, aka Dracunculiasis, is one of those horrible, horrible stories that people tell you about travelling to third world nations — in fact, it’s one of the most commonly bandied tales of woe. First, you swallow the baby worm with dirty water, at which point it happily chills out in your digestive tract for a year, before metamorphosing into something much nastier. It then migrates to a limb — usually a food — and forms a large and incredibly painful blister. You know how they get it out? They fish out one end, and pull it out slowly over the course of days or weeks of agony. You try and pull it out too fast, and it snaps, recoiling into the body to live again.

13. Trimethylaminuria, Fish Odor Syndrome

You have to feel sorry for the sufferers of Trimethylaminuria or fish odor syndrome. It’s exactly what it sounds like — a permanent pathological scent of rotting fish clings to your body. It’s actually linked to your metabolism, which interferes with the body’s ability to break down break down trimethylamine — which builds up and is excreted through saliva, sweat and urine. And that shit stinks bad! It’s incurable, recessive, and still around. I suppose at that point, you might as well become a fishmonger, and just blame it on the business.

12. Cancrum Oris

Cancrum Oris, commonly called Noma, is gangrene of the face, and for some reason it seems to hit kids more often than adults. More than 80% of those affected by the disease die, as it eats away at the tissue and musculature around their jaws. What causes it? It’s an opportunistic infection that likes to hop on board in situations where people are malnourished, have unclean drinking water, poor dental hygiene, and live in close proximity to farm animals. So pretty much anywhere unconscionably poor. What’s even worse is that it’s especially prevalent in the immuno-compromised, like HIV+ kids growing up in southern Africa. Ain’t life grand?

11. Cornu Cutaneum

Cutaneous horns are technically tumors, but seem to be more signs of satanic possession than anything else. It’s a tumor that causes horns to grow out your skin — which is even creepier because how in the hell do we even possess the mechanisms to grow horns? Hair, teeth, nails, all that stuff is already in the body, so when a tumor causes it, it makes some sense. But fucking horns? Well, technically it’s keratin, the same stuff as fingernails, but it’s still fucking creepy. And they don’t know what causes it, but they think it’s linked to HPV and radiation. Mmmm...sexually transmitted radioactive disease. Nice. Luckily you can just chop them off at regular intervals.

10. Fecal Vomiting

Okay, what does fecal vomiting sound like it is? Congratulations, you’re right. There are situations where you will literally vomit up fecal matter. How fun is that? What usually happens is that there’s an intestinal block of some kind, so the mushed up food can’t go all the way through the system. Instead it starts to back up, slowly pushing its way back into the stomach, where your body tries to get rid of it. And the only way out is up. You vomit up stuff that isn’t technically feces, but smells (and I bet tastes) exactly the same, because it’s partly digested food stuffs. Yay, the body.

9. Filarial Worm

Another fucking horrible parasite, but what makes this one even worse is the simple fact that it can live in your eye. Just...what? Why? Oh god, why would the universe create something as purely evil as a fucking parasite that lives in your fucking eyeball? Even worse, there are some leeches which will latch onto your eyeball. You know what’s super fucking creepy about the Filarial worm? It’s so common that it’s the second most common cause of blindness in the world. That means it happens to a fuckton of people. My eyes are itching just thinking about it.

8. Madura Foot

Madura foot, also known as Eumycetoma, is a chronic fungal disease of the foot. This isn’t anything pussy like athlete’s foot, this is an entire fucking tropical ecosystem established on your extremities. You get the fungal infection from working on farm fields, where the spores spread from the soil to open cuts on your feet, where they quietly take root, and don’t cause any pain, just some milky discharge, for up to a year. Then BAM enormous pus filled nodules all over your fucking feet...all the way down to the bone. There’s no vaccine or real cure for the disease, leaving the treatment to antifungals or amputation if they don’t work.

7. Pica

Pica is odd in that it’s a psychological disorder where people eat non-nutritious things constantly. Screws, chalk, mud, all sorts of things are devoured, but the cause is mental rather than a batshit virus or parasite causing them to act that way. At least in some forms they obsess over eating unusual food ingredients like raw flour, which I suppose is better than nails. See that photo just above? That’s the contents of the stomach of one patient in a psychiatric ward. That’s how bad it can get. It’s incredibly poorly understood what causes it, and the treatments are likewise nebulous and poorly defined.

6. Elephantiasis

Elephantiasis is one of those classic terrifying diseases, which causes massive thickening of the skin and underlying tissue, usually effecting the legs and male genitalia. Your scrotum can swell to the size of a basketball, which is not a sexy sight, I assure you. Like so much wrong with the world, it’s caused by a worm, its symbiotic bacteria and a mosquito. That’s right, those flying bastards can give you the parasite that’ll permanently destroy your lower half. Thankfully, this is one of those horrible, horrible disease that we’re actually beating, and it’s predicted to be all but eradicated by 2020.

5. Polyglandular Addison’s Disease

I thank whatever powers that be in the multiverse that this syndrome is so rare, because it scares the hell out of me. Seriously. What’s Polyglandular Addison’s Disease? Whenever you’re surprised, shocked, or under heavy stress, you get sick and could die. Scary movie. Close call on the road. April fools’ joke gone awry. A balloon popping. All could lead to your sudden and imminent demise. The sufferers can’t produce adrenaline, so when it’s meant to kick in for their systems, instead their organs go into shock and they could die. How fucking scary is that? If you have the disease, preferably not at all. Wouldn’t that suck? The doctor tells you, and the shock kills you off.

4. Necrotizing Fasciitis

Aaaahhh! AAaaaaaaaah! AaaahhhhhH! Whew, now that that’s out of my system...AAAAAAHHHH! Fucking hell. Necrotizing Fasciitis aka flesh-eating bacteria, are far more common than we want them to be, and any doctor you talk to will have seen the disorder at least once in their life. It tends to hit when you’re already suffering from something else: MRSA, immunocompromised, diabetes, alcoholism, etc. Even worse, if it gets you, there’s no saving the tissue. They just have to cut out the affected bit — ideally just a few small lumps of skin, but potentially a huge chunk of flesh, a limb, or even your testicles. That’s right, you can get it in your balls.

3. Harlequin Ichthyosis

Remember how I screamed about Necrotizing Fasciitis? Ditto. This incredibly deadly mutation causes babies to have super-thick skin which cracks where it should fold, leaving open wounds prone to infection. There eyes, orifices, and soft tissue are often painfully contracted, and moving can be agony for them. Currently, the odds of a child hit with the disease living are greatly improved, and there’s even a 27 year old survivor of the condition currently still alive, who’s the oldest survivor on record.

2. Fatal Familial Insomnia

How terrifying is this: you can’t sleep, and your insomnia is so bad that you die? This inhereted condition is untreatable, and usually kicks in at about the age of 50. Over the course of a couple of months, your insomnia gets worse and worse, leading to phobias and panic attacks. You start hallucinating and being unable to eat, which causes massive weight loss. You become increasingly demented, and become completely isolated and withdrawn, before finally dying. It’s a drawn out death sentence over the course of 7-18 months, with no cure, and a promise of agony and madness. Sleeping pills make it worse and speed up the disease. And it’s inherited. Next time you’re lying in bed, struggling to nod off at 2AM, remember this disease and start thinking about how well you’ve been sleeping of late...

1. Fibrodysplasia Ossificans Progressiva

This actually gives me nightmares. It’s a disease where your body’s repair mechanism is completely broken, and starts “healing” the fibrous tissue (read muscles, tendons and ligaments) by turning them into bone. That’s right, your whole body is slowly being petrified, as you excruciatingly transform into a creature formed of bone. Except, it’s bone without the smooth and mobile joints of the normal skeleton, so it’s like having a body filled with twigs that scrape and hinder every moment. Why not just cut off the growths? That causes the repair system to kick into overdrive, converting more of the body into bone and faster. There’s no known treatment for the 450 sufferers worldwide, and in one famous case a sufferer survived up to the age 40, at which point his entire body except his lips and transformed into bone, leaving him completely immobile. That’s fucking nightmare material.